Internal combustion method



July 22, 1941.

E'WE LL BEQ L EE "nrMosm/mlc PR5JUR VOLUME J'. J. WYDLER' 2,249,997

INTERNAL COMBUSTION METHOD Filed Nov. 12, 1938 2 Sheets- Sheet 1 Pereod@"JZ f .7 .61 J .9. 68% 7: 70 70 Period kre'ad Period Period Period54-36 34156-33 58-40 40-42 4Z'4'46 46-40-fl 1 F T F SH AlR PRE on$550+F| 1' FIRST' was? .srnoxe -psmoo 50-32 'g rrg gfF RE PRE RsREVOLUTION v fSECOND STROKE'PERIOD 32- FIRST COMPRESSION OF THIS CHARGE.

HHIRD, ,PER D flan coMaus'noN AND expmusuou BURNlNG- rms'r PART 05 FUELPERIOD 58-40 DISCHARGE 0F GA5EOU5 mooucrsor FIRST comaus-non A5 PUFFEXHAUST.

fFOURTH STROKE-PERIOD 4042 secouo COMPRESSION OF RETAINED UNUSED HOTAIR. {mm s'rRoKe-Pemoo4Z-44- INJECTlON OF sscouo PART'OF FUEL AND 46-40THIRD REVOLUTION SIXTH STROKE PERIOD M SECOND EXHAUST'DURING A COMPLETEEXHAUST STROKE.

.SECOND COMBUSTION AND EXPANSION INVENTOR ol/ANN d. W/DL R ATTORN EYJuly 22, 1941." WYDL R 2,249,997

INTERNAL COMBUSTION METHO D Filed Nov. 12, 1938 2 Sheets-Sheet 2 'g'COMPRESSION INTAKE I a: 6 Z9. 68 7? h v 74/ sxwlfis w 7 I N EXHAUST T f13 I H 56 H m m 152' J l? 5 ATTORNEY Patented July 22, 1941 INTERNALCOMBUSTION METHOD Jthanh J. Wydler, Westfield, N. 1., assignor, by

mesne assignments, to Cities Service Oil Company, New York, N. Y., acorporation of Pennsylvania I Application November 12, 1938, Serial No.240,013

successive piston strokes, which is a primary 11 Claims.

This invention relates to internal combustion engines, and more:particularly to an improved internal combustion operating cycle forefliciently and economically converting heat into mechanical work. Mycopendi ng application Serial No. 318,986 for Internal combustion enginewas filed February 15, 1940, as a division of the present application.

Many suggestions have been hereto fore made designed to increase theheat conversion efficiency of the internal combustion cycle. For exampleit has been heretofore suggested that the heat losses sustained throughradiation from the combustion zone might be reduced by lining said zonewith refractory or heat insulating material. Likewise it has beenheretofore proposed to reduce the energy loss normally sustained'throughdischarge of hot engine haust gases by employment of a compoundengine'equipped with'a second low pressure expansion cylinder operableto convert some of the energy still carried by the exhaust gases fromthe high pressure working cylinder into mechanical energy.

A primary object of the present invention is to provide an improvedinternal combustion cycle which is adapted for efilcient conversion ofheat of combustion into mechanical work even when practiced within theconfines of a single power cylinder.

of combustion cause of inefllclent airutilization by present operatingengines, as the basic feature of an improved six-stroke cycle internalcombustion operation adapted for practice with substantially theoreticalvolumes of air and fuel for complete combustion, and with reducedradiationlosses.

The improved engine cycle which forms the subject of the presentinvention may be carried out .in one or two working cylinders, and mayemploy precompression or air supercharging primarily as a means ofreducingpiston displacement of the power unit. All of the air usedduring the working cycle enters themain power cylinder during one airintake stroke. However, this air is burned in two portions during twopower strokes of a six-stroke cycle. A major part but not all of thefuel for one complete cycle,

is supplied and burned during the first power stroke. That portion ofthe air which is to be burned during the second power stroke is firstintroduced to the engine cylinder as substantially cured in theoperation of many present day internal combustion engines is theinefficient utilization of air and fuel supplied for combustion. For,example many present day Diesel engines operate on an air-fuel ratio inwhich the air exceeds by a considerable amount that theoreticallyrequired for complete combustion of the fuel, and the excess'alr notutilized for combustion carries away with it from the working space aconsiderable amount of heat as waste energy.

pure cold air during the first part of the air intake stroke, and duringthe latter part of the air intake stroke the air utilized in the firstpower stroke is introduced in preformed admixture with the fuel for thefirst power stroke. The air first introduced forms a stratified layeradjacent the piston head, and stratificatlon is maintained between thisair layer and the layer of combustible mixture as the piston reciprocatsthrough the intake and first compression stroke. first power stroke thislayer of air adjacent the piston forms an envelope orcushion between theburning portion of'the charge and the-piston and cylinder walls.

With a properly proportioned mixture of air and fuel undergoingcombustion during the first power stroke, a substantial part of the heatA reason for the need of this large amount of which would otherwise belost by radiation and conduction through the walls and piston head isabsorbed by the air envelope, and is thereby returned as excess powerduring the first power stroke by reason of the expansion of the volumeof the air envelope in proportion to its temperature rise. Thus aconsiderable part of the heat saving effected during the firstcombustion or power stroke can be converted into mechanical work withoutthe use of unnecessarily high operating temperatures and pressures, withresulting high heat losses in the exhaust gases such as occur when onlya refractory lining of the During the close and the pull ing athroat pfsubstantial area communicably 1o connecting the chamber with thecylinder bore, whereby to introduce gas into and remove gases from thecylinder while promoting conditions of gas stratification andnon-turbulence within the cylinder bore.

With the above and other objects'and features in view, the inventionwill be hereinafter particularly described with reference to theaccompanying drawings, in which: i I

Fig. 1 is a pressure volume diagram for an internal combustion processoperating on a cycle developing two power strokes in acycle of sixpiston strokes;

Fig. 2 is a diagrammatic vertical section of an engine showing therelative positions of the cylinder, piston and intake valve, just priorto completion of the first and intake stroke 30-42 of the six-strokecycle shown in Fig. 1;

Fig. 3 is a diagrammatic view showing the engine of Fig. 2 with thepiston at top dead center position 64 at the end of the second strokeand first compression stroke of the six-stroke cycle;

Fig. 4 is a diagrammatic view of the engine of Fig. 2 showing therelative positions of the parts at the beginning of the first powerstroke, or of the third cycle stroke;

Fig. 5 is a diagrammatic view showing the engine approaching the end ofthe first power stroke;

Fig. 6 is a diagrammatic view of the engine at substantially the bottomdead center position of the power stroke, with exhaust valve ready toexhaust finished;

Fig. 7 is a diagrammatic view of the engine showing the parts inapproximately the positions which they assume at the beginning of thesecond power stroke, or at the end of the fourth cycle stroke;

Fig. 8 is a diagrammatic view of the engine showing the relativepositions of the parts at approximately the end of the second stroke orof the fifth cycle-stroke;

Fig. 9 is a diagrammatic view of the engine showing the relativepositions of the parts just prior to the end of the sixth and lastexhaust stroke 4048 of the cycle;

Fig. 10 is a chart briefly outlining the principal steps of the cycle;

Fig. 11 is a view in elevation of a preferred design of one cylinderpower plant adapted for the practice of the process of the invention,part of the working cylinder and valve chamber and part of thecarbureter being shown in vertical section;

Fig. 12 isa plan section of the cylinder head of the first .four pistonstrokes of the six-stroke cycle.

The process can be carried out within a plant including a single powercylinder, or in two cylinders which may be termed a primary. and asecondary cylinder. While the drawings illustrate a power plant in whichthe cylinders are disposed on a vertical main axis, the cycle can bejust as well practiced in a power plant having horizontally disposedcylinders, or having cylinders disposed at any angle to the horizontal.

Referring to Fig. 1 and to Fig. 10, it will be seen that a completeprocess cycle develops two power strokes during aperiod of six pistonstrokes, and thus may be termed a six-stroke cycle process. The diagramarea 32, 34, 36, 38 of the first power stroke (Fig. 1) is substantiallyequal to or better than the output of any commercial engine, while thesecond diagram area ll, 42, ll, 46 represents the power developed as aresult of reduction in heat loss and more eflicient utilization ofcombustion air and fuel. In

the engine of Fig. 11, taken on the line l2-I2 length of the airdischarge portion of the cycle u carried out in the engine of Fig. 13,durin other words, the area l0, 42, 44 and 46 substantilally representsthe actual improvement I of the power cycle of the present inventionabove prior standardengineperformance. Of course the thermodynamiceificiency' of the herein described power cycle can be still furtherimproved by employing one or more gas turbines to convert to mechanicalpower some of. the energy carried by the hot exhaust gas discharged fromthe engine.

vAs illustrated in Figs. 2 to Fig. 12 inclusive, the principal elementsof a power plant adapted for practicing theprocess include a workingcylinder 80, a piston 58 mounted for reciprocation in the cylinder, andan ignition and valve chamber 66 positioned at' the combustion end ofthe cylinder and communicably connected therewith by a throat 52 havingan area which is at least one-fourth of the total cross-sectional areaof the cylinder. An air and fuel intake valve 68 and an exhaust gasdischarge valve 10 are mounted within the chamber 66. The totalcombustion clearance space within the engine when the piston is at topdead center position (see Fig. 3) is made up in part of a flat cylinderspace 62 between the piston and the head of the cylinder, and in part ofthe valve chamber 66. In a power plant in which both power strokes ofthe sixstroke cycle are to be carried out in a single cylinder, a fuelinjection nozzle 12 is positioned at the combustion end of the cylinder(Fig. 7), in position to inject atomized fuel under pressure pasta valve13 into chamber 66 and clearance space 62. According to the preferredplan of operation, as practicedrinone cylinder, the fuel injectionnozzle 12 is onlyoperated at the be--- .pipe 14. The precompressed airis preferably cooled down to substantially atmospheric temperature priorto its introduction to the working cylinder by passage through the coilsof an intercooler or heat exchanger 56. Water or other cooling liquid ispassed through the intercooler by pipe 55. According to the preferredcycle, the fuel which is used up during the first power stroke ispreadmixed in correct proportion for perfect combustion with thatportion of the'air used up in the first power stroke, before the air.and fuel mixture enters the working cylinder.

cycle is taken in from the cold air supply pipe intake stroke, the gaseswithin the cylinder with- This preadmixture or precarburetion of the airand fuel used in the first power stroke is effected by a carbureter 16mounted in the air supply pipes 14, such carbureter having a fuelinjection nozzle 18 by which the fuel is atomized into the air streamflowing toward the intake valve 68 during the intake stroke. A valve 11controls supply of fuel to the nozzle 18.

In Fig. 3 a hot spot ignition cell 88 is shown as ported out intochamber 66 at a point adja- -cent the exhaust valve I8. With thislocationthe cell 80 retains at all times a considerable. amount of heatand can function as an igniting element for the air-fuel charge in thecylinder at the beginning of the first power stroke. 15

As shown in Fig. 11, provision is made for water-cooling the upper partof the working cylinder and the ignition and valve chamber. However,water cooling is not absolutely necessary for the cylinder .walls if theengine is operated on the preferred cycle of the present invention.

A power! cylinder suitable for practicing the process of the inventionmay be operated with a compression ratio in the range 5-8, or in otherwords with substantially the same compression ratio as any gasolineengine. Since, according to the preferred cycle, the air for the firstpower stroke is precompressed to a maximum of about 40% of its originalvolume, the engine. may operate with an-overall compression ratio ofbetween 12 and 20.

In practicing the cycle in a single cylinder power unit, the air andfuel intake valve 68 is only open during the first of three enginerevolutions making-up the cycle. The exhaust valve i 10 operates duringthe second revolution of the engine and again during the thirdrevolution. While not specifically illustrated, it will be understoodthat the intake and exhaust valves may be suitably actuated and timedfrom the engine crank shaft.'

The complete operating cycle will now be described,-as practiced in asingle cylinder power unit of the type illustrated in Figs. 2 to 9, in-.r clusive, 11 and, 12.

Referring to Fig. 2, which corresponds to the period 38-42 in Fig. 1,the intake valve 68 remains open during the first stroke of the piston,and the total air charge for a complete 14. -Normally the first 30%40%ofthe air charge is taken into the cylinder as clean cold air during thefirst part of the intake stroke. During the last part of the intakestroke the balance of the air for the complete cycle is taken in in theform of a preformed fuel-air mixture, the fuel being introduced into theair at the carburetor 16. By thus admitting the air for both powerstrokes in successive periods of the the piston 58 in the position shownin Fig. 2, will consist of a strata of pure cold air above the pistonand below the imaginary dividing line 84, while that part of thecylinder lying above the dividing line 84 is filled with an air-fuelmixture, the components of which. are in substantially theoreticallycorrectproportions for perfect combustion during the first power stroke.

While some stratification of successively inassure such stratificationby providing an igniaziepe'r imaginary dotted line I02.

tion and valve chamber 66 at the combustion end of the cylinder havingsufflcient volume to make up the major part of the desired clearancespace, and by providing a throat 52 of substantial area, i. e., at leastone-fourth the area of the cylinder, communicably connecting suchcombustion space with the cylinder proper. By this construction any airor air-fuel mixture which is admitted past the inlet valve 68 at highvelocity is forced to spread out in all directions within the valvechamber 66 across the whole width of the cylinder bore. In doing so-therate of flow is slowed down in amount inversely proportional to theincrease of cross-sectional area of flow within the chamber. By thattime any kinetic or inertia energy which might have been able to upsetor disturb stratification of gases flow through the throat 52 to fill upthe cylinder space according to the principle of continuity. The air isnormally introduced to the cylinder in a precompressed state andpreferably after intercooling down to a temperature of about F. (560 F.abs).

After the successive introduction of pure air and air-fuel mixture hasbeen effected during the intake stroke in such a way as to promotestratification of the bodies of air and air-fuel mixture-.- siichstratification is readily maintained during the succeeding compressionand power strokes. As shown in Fig 3, the combustible mixture has beencompressed at the end 64 of the compression stroke into the ignition andcombustion chamber 66, with'the body of pure air underlying thecombustion mixture below. the imaginary dividing line 86, in theclearance space 62. The temperature of both layers of compressed gas israised during the compression stroke to an absolute temperature of about1000 F. as a result of substantially adiabatic compression. I i

During the compression stroke a small portion of the combustiblemixtureis forced into ignition cell 80, which is so constructed that itremains in a substantially red hot condition throughout a'completeoperating cycle; or a glow bar or spark plug 88 (Fig. 11) may bedisposed at the end of the cell 88 for the purpose of igniting thecombustion mixture compressed into the cell at substantially the topdead center position 64 of the piston 58.

After ignition the combustible mixture in chamber 66 starts to expand atthe beginning of the power stroke, the front wave of the body ofexpanding gases assuming substantially the position outlined by theimaginary line I08 in Fig. 4. I

This expansion continues as shown in Fig. 5, driving the piston 58toward its bottom dead center position, the stratification interfacebetween the expanding products ofcombustion and the pure air assumingsubstantially the position of the The curvature assumed by thisinterface I02, will vary with variations in the area ratios of thethroat52 and cylinder 60, and with variations in the volumetric ratios of thecombustion spaces inside valve chamber 66 and cylinder clearance space62. It will of course be appreciated that the imaginary lines designated84', 86, I08, I02 and 92 in Figs. 2, 3, 4, 5, and 6, are intendedto'indicate the position of the interface between the air and gas stratawithin the cylinder, as' such interface would be outlined whenviewed invertical cross section. There is no difilculty in maintaining suchtratification in either horizontally or vertically disposed cylinders,over so short a period as is available for each individual cycle of highspeed engines. Such curved gas interfaces are commonly illustrated byexperiments on acoustical vibrations wherein the gas layers oscillate atvery high frequencies. However the piston oscillations in enginesoperating at the highest rotational speeds develop gas vibrations verymuch below the frequencies of sound.

As shown in Figs. 4 and 5, the considerable expansion'in volume of theignited and burning gases which form the upper gas layer in the cylinderand chamber 66, effects additional compression of the air forming thelower gas layer, and since the original ignition and expansion largelytakes place within a chamber 66 and connecting throat 52 having across-sectional area normally smaller than that of the cylinder proper,the resulting expansion of hot gases into that zone of the cylinderpreviously occupied by the air forces the air outwardly as w l asdownwardly into closer contact with the ylinder walls 60 and the piston58 (Fig. 5). Thus the compressed pure air below the interface I02 inFig. 5

functions as. an insulating and heat absorbing cushion preventing directcontact between the combustion products and cylinder walls and piston,and the otherwisewasted heat is absorbed into the air instead of beinglost to the walls by radiation, convection, and conduction during thisfirstspower stroke.

According to the present invention the first power stroke isconducted'with a distinct and very hot core of combustion products andwith a relatively cool ambient ai envelope, as against standardprocedure wheren a substantially nomogeneous mixture of burned gases andunburned air is in direct contact with the walls. Due to the poor heatconductivity of gases in general, very large differences in temperaturecan and will be maintained between the excess air and burning gasesduring individual power strokes. Thus the excess air envelope in thecylinder of an engine operating on the cycle of the present invention isnot heated as much as the same proportion of excess air weight would beheated in a Diesel engine, for example, operating with a homogeneouscylinder mixture of the same air-fuel ratio. Furthermore, when the aircomponent of the charge is precompressed'and of combustion products isexhausted from the cylinder by the first pufl exhaust, and the originalexcess air is retained for the fourth,.fifth and sixth strokes in asufliciently preheated state from the first power stroke to fill up thecylinder space at about atmospheric'pressure, or at about exhaustreceiver pressure when an exhaust gas turbine is employed. The term"puff exhaustrefers to the rapid expansion discharge of a portion ofgases due to the inherent pressure energy of the total weight of gasesin the-cylinder at the time that the exhaust port opens.

During the fourth stroke this r'arified air is given the same moderatecompression as was applied during the second stroke, with acorresponding moderate adiabatic rise of its temperature level. Thistime, however, the compressed air charge is finally heated to acompression and temperature high enough to assure self ignition ofsolidly injected fuel, since the compression started with the airalready well preheated.

The fifthand sixth strokes of the cycle are entirely similar to thepower and exhaust strokes of a standard four cycle engine.

Another important feature of this power cycle is the definiteelimination of the detrimentally high peak explosion pressuresencountered in modern high speed Diesels. Although in the first powercycle the core of the charge is an almost theoretically correct mixture,the overall charge air fuel ratio is lean. The second power strokeoperates at a peak pressure substantially the same as that of a moderategasoline engine cycle; however its air-fuel mixture must be keptslightly leaner to avoid smoky combustion.

The relative positions of the principal parts of the power unit duringthat second part of the cycle in which the unburned part of the originalair charge is compressed, burned, and exhausted, has been illustrated inFigs. 6, "I, 8 and 9.

In Fig. 6 the exhaust valve 10 has been shown in open positionpermitting discharge of the exhaust gases from the cylinder into acollector or gas turbine (Fig. 11) against a back pressure, preferablyof about 30 pounds'absolute (corresponding to point 40 of Fig. 1). Thusthe lower strata of air within the cylinder is permitted to expand downto this pressure level and to occuintercooled before its introduction tothe cylinder,

the compact body of excess air is present inside the cylinder in acooler state, and because of the larger temperature gradient therebyexisting between the air and burning gases, the air cushion can acceptand return immediately as power in excess over the compression work,much of the heat radiated from the hot burning gas core, permitting verylittle heat transfer to the cylinder walls.

Such mechanism of heat exchange within the total gaseous cylinder chargemay be utilized advantageously either to produce an indicator card ofgreater area, or preferably to produce the same size of indicator cardarea with a fuel charge smaller to the extent of heat prevented fromentering the cooling walls. The core of combustible and compressionstroke.

mixture in thiscase can be kept either of smaller proportion or of asomewhat leaner composition, assuring better combustion withoutdissociation, and the puff exhaust gas will not be too hot.

At the end of the third stroke the burned core py substantially thetotalcylinder space, thereby scavenging the cylinder of combustionproducts. The exhaust valve is then closed and the air remaining in thecylinder is recompressed as shown in Fig. 7 to a final pressure whichmay be substantially two-thirds of the peak pressure developed in thecylinder during the first compression stroke. Atthe same time thetemperature of this air rises to about twice the absolute temperature ofthe air at the beginning of this sec- In other words, the temperature ofthe air after this second compression is such as to allow .forself-ignition oi the combustion mixture formed by pressure injection ofthe second charge of fuel through the nozzle 12 (Fig. 7). J

While the preferred operating cycle contemplates use of a carbureter ISin the air supplyline for the purpose of producing a combustible mixtureof air and gas which is.

well-balanced burned during the first power cycle, it will beappreciated that the combustible mixture for the.

the second stage of the air intake stroke. The use of the carbureter I6is preferred to insure the most eflicient mixing of the air and fuelwhich is to be used during the first power stroke.

The apparatus of Fig. 11 has been illustrated to include means wherebythe body of air which is admitted to the cylinder for use during thesecond power stroke may be cooled, while the air which is mixed withfuel for combustion during the first power stroke is admitted to thecylinder without intermediate cooling. To effect this result, thesection of the air pipe 14 within which is located the intercooler 56and carbureter I8 is mounted in parallel or shunt with another sectionof pipe 82 within which there is mounted a carbureter 90. A pair ofshuttle valves I06-I08 is mounted in position to control circulation ofair from the compressor either through pipe 82 and carbureter 90, orthrough the intercooler 56 and carbureter 16. As shown, these shuttlevalves may be rotatably mounted on a shaft IIO actuated from the enginecrank shaft I I2 at a speed which is proper for regulating introductionof successive proportional volumes of cool fresh air and hot carburetedfuelair mixture to the cylinder during the intake stroke. Thismodification of the preferred apparatus to include the bypass connection82 and carbureter 90 together with the shuttle valves I06 and I03 andthe actuating mechanism there-.- for, is particularly adapted to a cyclemodification according to which during the first intake stroke a majorpart of the cycle air is'conducted through the intercooler 56 to thecylinder 60, and during the last part of the intake stroke the remainingminor portion. of the air passes through the carbureter 30 in a heatedstate where it is charged with fuel to provide an over-rich mixture. nthe compression stroke this overrich mixture is further heated and mayreach a self-ignition temperature at the top dead center position of thepiston.

The relative proportions of fresh air and airfuel mixture admitted tothe cylinder during the first intake stroke may be widely varied.Normaliy it is preferred to admit about 30-40% of the air used in thecomplete cycle as cold fresh air during the first part of the intakestroke, and during the last part of the intake stroke to admit thebalance of the air in an air-fuel mixture containing approrimately"60-'70% of all of the fuel which is used during the completecycle.

The type of carbureter I6 which is illustrated in Fig. 11 is designedparticularly for use with a relatively low pressure fuel supply feedinga jet, the feed to which may be controlled by a needle valve II operatedfor example by suitable cam mechanism connected to the crank shaft. A

In a multi-cylinder engine the present sixstroke cycle process iscarried out within two cylinders, the primary cylinder operating on afour-stroke cycle, and a secondary cylinder operating on a two-strokecycle. In the particular engine illustrated diagrammatically in Fig. 13,three cylinders are provided, two of which operate on four-stroke cyclesas primary cylinders, while a third cylinder operates on a two-strokecycle as a secondary cylinder. A complete pressure volume diagram of thecycle as carried out in this multi-cylinder engine is the same as thatfor the one-cylinderengine as illustrated in Fig. 1.

The engine illustrated in Fig. 13 is equipped with two primary cylindersI20-I22 operating on four-stroke cycles. Piston I24 in cylinder I20 isillustrated-finishing its compression stroke, while piston I26 incylinder I22 is shown completing. its exhaust stroke. Piston I28 in thesingle secondary cylinder I30 operates on a twostroke cycle, and isillustrated in the position assumed at the end of its own secondarycompression stroke and the beginning of its power stroke. All threecylinders are illustrated as operating on the same crank angle. However,one primary cylinder always operates on a third stroke of its cyclewhile the other primary cylinder is operating on its first stroke, or inother words, the primary cylinders operate on cycles which have a 360crank angle spacing.

The first three strokes of the operating cycle for each of the cylindersI20 and I22 follow substantially the same cycle as for the singlecylinder six-stroke engine previously described. These steps areillustrated by Figs. 2, .3, 4, and 5. In the engine of Fig. 13, however,each of the cylinders I 20 and I22 is provided with side wall airexhaust ports I32 which are uncovered by the pistons I24 and I26 as the'pistons approach bottomdead center position. A pair of conduits or.transfer passages I34 communicably connect the side wall discharge portsI32 of primary cylinders I20 and I22 with air inlet ports I36 openinginto the combustion end of secondary cylin der I30. Flow of gas throughthe conduits I34 is regulated by a pair of apertured plunger valves I38and I40 each operatively associated with one of the conduits I34. Theopening and closing of valve I38 is preferably effected from a cam shaftI42 in timed relation to the position of piston I24 in cylinder I20; andlikewise the opening and closing of valve I40 is effected in timedrelation to the piston I26 in cylinder I22. In other words, asilllustrated in Fig. 14, valve I38 is opened for a crank angle period ofsay sixty to ninety degrees during each four-stroke cycle of piston I24in cylinder I20, and the same is true with respect to valve I40 and thepiston in cylinder I22. Valves I38 and I40 preferably open about 45crank angle ahead of the bottom dead center position of theircorresponding pistons I24 and I26 during the expansion or power strokeof the pistons. Likewise the valves I38 and I40 are preferably timed toclose about 45 crank angle beyond bottom dead center position of thecorresponding piston on the exhaust stroke of the piston. The valves I38and I40 are of course timed to remain closed during all other portionsof the four stroke piston cycle practiced in each of the cylinders I20and I22.

During the period in which each of the valves I38 and I40 remains open,the body of air which forms the lower layer of gases in thecorresponding cylinder I20 and I22 during the power stroke (see Fig. 5),is forced out from the corresponding primary cylinder through thecorresponding conduit I34 into the combustion .end of the secondarycylinder I30 through air intake ports I38. At the time that thistransfer of air takes In other words, exhaust ports I44 in cylinder I30are uncovered by the piston I28 during the period in which the piston ispassing through its bottom dead center position. Therefore introductionof air from one of the primary cylinders into the combustion end of thesecondary cylinder I30 serves the double purpose of-scavenging cylinderI30 of products of combustion produced therein during the precedingpower stroke, and filling the cylinder with preheated air preparatory tothe compression stroke of piston I28.

At the end of the secondary compression stroke in cylinder I30 fuel forthe secondary power stroke is injectedthrough a high pressure injectionnozzle I46, and on the power stroke ignition and combustion of theair-fuel mixture takes place in the cylinder, producing a pressurevolume indicator card substantially as outlined by the area within thecurves 40-424446 in Fig. 1. During the-exhaust strokes of the pistons ineach of the primary cylinders I and I22, the products of combustionremaining in the corresponding cylinder after discharge of the lowerlayer of air into the secondary cylinder, are exhausted into the openatmosphere or into an exhaust receiver or exhaust turbine I48,preferably against a relatively low back pressure.

As will be appreciated, each of the primary cylinders I20 and I22 is soconstructed as to follow closely in design and operation the singlecylin-- der engine which is illustrated in Figs. 2 and 11. Each of thecylinders I20 and I22 is preferably equipped with an ignition and valvechamber 66 at its combustion end, which chamber corresponds in designand function with the corresponding chamber 66 of the single cylinderen- *to sever heat stresses for the reason that the weights of hot gashandled in the secondary cylinder I are considerably lower thancorresponding values for the usual two-cycle engine.

The engine which is illustrated in Fig. 13 is designed with the pistonsof each of the three cylinders operating on the same crank angle. Itwill be recognized, however, that the piston of the secondary'cylinderneed not operate on the same crank angle as the pistons of the primarycylinders, since by reversing the position of this cylinder so that thecombustion end of the cylinder is at the lower end of the piston stroke,the piston can be operated at a crank angle spaced 180 in phase from thecrank angle common to the pistons of the high pressure cylinders.

Fig. 13 illustrates diagrammatically how the operation of each of thegas flow control valves as well as of the pistons and fuel valves can beeffected and timed from the main engine crank shaft I50. The timing ofoperation of the valves for controlling air admission and air and gasexhaust with respect to the primary cylinders follows the valve diagramof Fig. 14. According to the design illustrated, each of the valves 68,I0. I38 and I40 is actuated from cam shaft I42 by means of connectingrods and cams or eccentrics gine. Air inlet valves 68 and gas exhaustvalves I0 are mounted in the valve chambers 66 of each primary cylinder.Air valves 60 function to control the successive admission of pure airand of precarburetted air-fuel mixture to the valve chamber, and thencethrough a throat 52 into the working cylinder proper, during the intakestroke of the piston. Likewise exhaust valves I0 operate-to permitoutflow of waste combustion gases from the cylinder and valve chamber 66during the exhaust stroke of the piston, following the closing off ofthe air discharge ports I32 and connecting conduit I34, withinapproximately the first 45 movement of the crank operating the pistonbeyond bottom dead center on its exhaust stroke.

A design feature of the combustion end of the secondary cylinder I30consists in having the air supply conduits I34 and the tangentiallyarranged ports I36 directed upwardly or toward the cylinder head.Likewise the head of the cylinder I30 is preferably built with a conicaltaper, with the -.fuel injection nozzle I46 located at the apex of thecone. By this construction highly eflicient scavenging is assuredbecause the inflowing air builds up a compact and stable rotating gascylinder, growing at a steady rapid rate and moving downwardly to forcefrom the cylinder space gaseous productsof combustion produced duringthe preceding power stroke.

While the secondary cylinder I30 operates on a two-stroke cycle, thisoperation is effected without the usual port difliculty experienced intwo-cycle engines. ,In the first place it is only preheated air, and notvery hot combustion products, which is to be transferred from cylindersI20 and I22 by way of the ports I32 and admitted through the admissionports I36. Furthermore the exhaust ports I44 are not subjected rotatablyconnected to the cam shaft. The cam shaft I42 is in turn driven fromcrank shaft I50 at half the speed of the crank shaft, by means ofaconnecting shaft I52 and suitable connecting gearing. Each of thepistons I24, I26 and I28 is connected directly to the drive shaft bypiston and connecting rods, cross heads and cranks. While Fig. 13includes no illustration of specific means for supplying the air andfuel to the primary cylinders of the engine, it will be appreciated thataccording to the preferredcycle such means would include an aircompressor, air interoooler and fuel carbureter 16, preferably arrangedsubstantially in the same relative relation as the correspondingelements 54, 56 and 16 associated with the single cylinder engine ofFig. 11.

By carrying out theinternal combustion operation in accordance with thepreferred six-stroke cycle, burning the fuel supply for one cycle in twopower strokes, it is possible to secure emcient combustion withoutdeveloping excessive pressures within the cylinder on either powerstroke, thereby assuring safe operation and norratio lying insubstantially the same range as thecompression ratios for standardcompression ig-.

nition engines of the Diesel type. while holding the pressures developedwithin the cylinders well within gasoline engine practice. By operatingon a cycle which employs precarburetion of the fuel-air charge which isburned during the first power stroke, substantially combustion efliciency can be assured for this stroke even though ignition of themixture is effected by means of a spark or hot spot ignition element.Even the use of the spark or hot spot element during the first powerstroke has its advantages. In the first place this insureseasierstarting of the engine as compared to self-ignition engines; andin the second place an opportunity is afforded for operating the enginewith efficient combustion during idling, as by cutting out the secondpower stroke and operating the engine only on one power stroke for eachsix-stroke cycle. Thus by the power stroke of the cycle.

preferred cycle of the present invention, that portion of the fuelcombustion which takes place during the first power stroke developsunder conditions closely resembling those existing in standard slowspeed engines operating with nearly constant pressure combustion,whereas the combustion occurring during the second power stroke isreadily controlled as to the pressures developed mainly by regulatingthe volume of excess air which is present as a heat-absorbing gascushion during combustion in the first power stroke.

The invention having been thus described, what is claimed as new is:

1. In an internal combustion operating cycle developing two fuel intakeperiods, two air compression periods, two power strokes and two gasexhaust periods in a cycle of six piston strokes, the steps comprisingintroducing air for combustion in the second power stroke into thecombustion end of a cylinder during the first part of the air intakestroke, during the second part of the air intake stroke introducing apreformed mixture of air for the first power stroke together with thefuel for the first power stroke and at the end of the first power strokeseparating gaseous products of combustion produced thereby from the airfor the second power stroke.

2. The process as defined in claim 1 together with the step ofintroducing the charges of airand air-fuel mixture during the air intakestroke in successive non-turbulent uniflow streams to promotestratificationof the air and air-fuel bodies within the cylinder duringsuccessive piston strokes.

3. The process as defined in claim 6 in which the air for the secondpower stroke is precompressed and then cooled before into the cylinder.

4. In an internal combustion process developing two power strokes in acycle of six piston strokes, the method of practicing such cycle withina primary cylinder operating on a fourstroke cycle and a secondarycylinder operating on a two-stroke cycle which comprises, introducingcold air for the second power stroke into the combustion end of theprimary cylinder during the first part of its intake stroke, introducinga preformed mixture of fuel and air for thefirst power stroke into theprimary cylinder during thefi'atter part of its intake stroke,maintaining stratific ation oi the successively introduced bodies of airand air-fuel mixture within the primary cylinder during the succeedingcompression and power strokes, and transferring the air for the secondpower stroke in a preheated condition from the primary cylinder into thecombustion end of the secondary cylinder at the end of the first powerstroke in the primary cylinder.

5. The process as defined in claim 4 together with the step ofcompressing the preheated air thus introduced within the secondarycylinder, injecting suflicient fuel into the secondary cylinder to reactwith the compressed air, and igniting and burning the combustion mixturethus formed in the secondary cylinder during the second 6. In aninternal combustion operating cycle developing one air intake stroke,two fuel intake periods, two air compression periods, two power strokesand two gas fexhaust periods in a cycle of six piston strokes, the stepscomprising, successively introducing into the combustion end of acylinder duringthe first intake stroke non-turbulent streams ofsubstantially pure air and of a precarbureted mixture of air and fuel,during the second stroke compressing the bodies of pure air and air-fuelmixture while holding said bodies in contacting stratified relation withthe air body in the piston end of the cylinder, at the end of thecompression stroke and the beginning of the first power stroke, ignitingthe air-fuel mixture and expanding'the products of combustion into theheat absorbing cushion of air thus compressing the air strata, andmaintaining such stratification between the compressed and preheated airand the hot products of combustion at the end of the first power strokewhile separating the air and products of combustion preliminary toutilization of the air in the second power stroke.

7. The process as defined in claim 6 as practiced within a singlecylinder, in which separation of the air and hot products of combustionis effected at the end of the first power stroke and at the beginning ofa fourth recompression stroke by a puff exhaust of products ofcombustion from the cylinder while expanding the air strata to fill thecylinder, recompressing such air during the fourth stroke, injectingsufiicient fuel into the thus recompressed air to burn the same, andigniting and burning the fuel air mixture thus formed in a second powerstroke.

8. The process as defined in claim 6 when its introduction three cyclesteps are carried out in a primary cylinder with separation of thepreheated air and products of combustion taking place at the end of thefirst power stroke and at the beginning of the fourth exhaust stroke inthe primary cylinder by effecting a puff discharge transfer of the airfrom the piston end of the primary cylinder into the ignition end of thesecondary cylinder while simultaneously scavenging the secondarycylinder, during the next stroke in the secondary cylinder compressingthe preheated air thus introduced, injecting fuel into the air at theend of the compression stroke, and igniting and burning such fuel-airmixture during a second power stroke in the secondary cylinder.

9. The method of converting heat into power in a reciprocatinginternaLcombustion cylinder operating on a cycle of 6 piston strokes,which comprises, during the first intake stroke introducing into one endof the cylinder in a slow-moving columnar stream coaxial with thecylinder and having a cross-sectional area not less than one quarter ofthe cylinder area substantially 30%- of the cycle air as pure air,during the bal-.- ance of the intake stroke introducing into the.

cylinder a similar stream carrying the remaining 60-70% of the cycle airpreadmixed with a major portion of the cycle fuel, during the secondstroke adiabatically compressing the charge while maintaining the airfirst introduced and the air-fuel.

last part of the fourth stroke recompress ng the hot air remaining inthe cylinder, at the end of the fourthstroke injecting a minor portionof cycle fuel into the thus-compressed air and igniting the mixture,duringthe fifth working stroke expanding the products of the secondcombustion, and during the sixth stroke discharging the products of thesecond combustion preliminary to a second cycle.

10. The method of converting heat into power in a reciprocating internalcombustion engine having two cylinders, the first operating on afour-stroke cycle and the second on a two-stroke cycle, which comprises,introducing pure air into the first cylinder in a slow-movingnon-turbulent stream during the first part of its intake stroke,introducing a preformed mixture of air and fuel into this cylinder in aslow-moving non-turbulent stream during the balance'of the suctionstroke, during the second stroke'in this first cylinder compressing thebodies of air and air-fuel mixture while maintaining stratification,during the power stroke in the first cylinder igniting the airfuelmixture and expanding the products of como burning the mixture on thepower stroke of this cylinder, and discharging productsoi combustionfrom this second cylinder on its second stroke while simultaneouslyoperating the first cylinder on the first intake stroke of its nextfour-cycle operation.

11. In an internal combustion operating cycle developing two fuel intakeperiods, two air com pression periods, two power strokes and two gasexhaust periods in a cycle of six piston strokes, the steps comprising,introducing air for combustion in the second power stroke into theignition end of a cylinder during the first part of the air intakestroke, during the second part of the air intake stroke introducing apreformed mixture of air for the first power stroke and fuel for thefirst power stroke, maintaining stratification of the successivelyintroduced bodies of air and air-fuel mixture within the cylinder duringthe succeeding compression and power strokes, after the first powerstroke separating the air for the second power stroke from combustiongases formed during the first power stroke and discharging thecombustion gases, compressing the air thus separated, admixing fueltherewith, burning the mixture thus formed during the second powerstroke, and discharging products of combustion thus formed.

, J OHANN J. WYDLER.

